Polymer compositions are generally useful in manufacturing objects by employing techniques commonly used with thermoplastic materials, e.g., injection molding, extrusion, blow molding, melt spinning, and stamping. Semicrystalline and amorphous polymers are commonly blended together to obtain polymer compositions having desirable physical characteristics.
Unfortunately, many semi-crystalline and amorphous polymer compositions can be brittle and crack upon impact making them undesirable for certain applications requiring high impact resistance, for example, in the fabrication of automobile body panels. The desire to improve toughness of polymer compositions has led to the use of impact modifiers, also known as elastomers or elastomeric polymers. Impact modifiers improve the toughness of an otherwise brittle polymer composition by imparting elastic properties to the polymer composition. Generally, the impact modifiers are melt blended simultaneously with the semicrystalline and amorphous polymers to produce a polymer composition which is then injection molded or otherwise formed into a desired shape.
Gallucci et al. U.S. Pat. No. 4,873,286 discloses an improved process for the manufacture of polyphenylene ether-polyamide compositions wherein a polycarboxylic acid modifier is precompounded with either the polyamide or, preferably the polyphenylene ether prior to compounding with the other polymer. The polycarboxylic acid modifier is employed to modify surface properties of the resulting polymer composition. The polycarboxylic acid modifier is not an impact modifier. Gallucci et al. broadly suggests that other components such as impact modifiers, reinforcing agents, stabilizers and the like, may optionally be precompounded into the resulting polycarboxylic acid modified polyphenylene ether-polyamide compositions.
It has also been suggested to initially blend a butadiene copolymer with a polyamide prior to blending with a polyepoxy compound. See Sasaki et al. U.S. Pat. Nos. 4,567,235 and 4,567,238. Additionally, Flexman et al. U.S. Pat. No. 4,942,200 discloses preblending a polyarylate and an epoxy functional polymer before blending with either a polyamide or an elastomeric modifier. It is also known that certain impact modifiers preferentially disperse within poly(phenylene oxide) rather than Nylon-6,6 in a poly(phenylene oxide)-Nylon 6,6-polymer composition. This is discussed in an article entitled "Morphology and Properties of Toughened Poly(Phenylene Oxide)-Polyamide Blends", Hobbs, S.Y., Dekkers, M.E.J. and Watkins, V.H. Journal of Materials Science vol. 24 pp. 2025-2030 (1989).
A need exists to develop sequentially mixing or preblending components to obtain certain physical characteristics of a semicrystalline and amorphous polymer blend to accommodate various utilities.